Molded product



UNITED STATES.

CROSS REFERENCE LMMINLK PATENT orrlcs MOLDED PRODUCT Allan B. Huddle,San Francisco, Galif.

No Drawing. Application December 10, 1937,

Serial No. 179,150

liclaims. (oLzz-1ss)z This invention relates to molded products, andparticularly to a composition for molding which has as its principalingredient sand or other similar granular or powdery substance.

The present application is a continuation in part of my. copendingapplication entitled Molded product, Serial No. 165,765, filed September25, 1937. The said oopending application describes a method for andproduct of moldinz from sand and the like for manufacturing variousarticles, and particularly for making foundry cores for metal castingpurposes.

The present invention relates particularly to such cores. The cores usedin foundry practice are usually constructed of ordinary molded sand withingredients added to facilitate molding the sand to a definite shape,and permit baking or curing the core to render it sufilciently hard orfirm to stand up under the pouring of molten metal, yet friable enoughto be readily broken out of the completed casting.

The object of the present invention is to provide a molded articleparticularly adapted for use as a foundry core which is formed entirelyof relatively inexpensive materials, and to provide a core which,although having exceptional resistance to breakage by the pouringagainst it of molded metals, will upon cooling or setting of the metalbe so easily broken that it will readily return to its granular orsand-like form.

A further object of the invention is the provision of a 'core thatwillsbe capable of drying or being cured very rap dly. and a, core inwhich the drying and effect of drying will be uniform throughout.

Another object is the provision of a core having a minimum tendency tostick or adhere to the mold or core box to which it is formed.

1 have discovered, as set forth in my copending application abovereferred to, that a satisfactory molded core may be made by mixing withcommon molding sand an alkali metal silicate, an

alkali metal fiuosilieate, and either an acid or anal It is preferredthat the materials used forthis purpose be such as are available atrelatively low cost. Sodium silicate and sodium fiuosilicate meet thisrequirement and are typi- 0' al of the alkali metal silicates andfiuosilioates that may be used. Aluminum sulphate is an example of aninexpensive alum-like substance that is suitable for the purpose of thepresent-invention. In making cores, I first prepare a solution in theproportions of about 2 gallons water 1-10 ounces aluminum sulphate 1-10ounces alkali fiuosilicate, and 1-10 gallons of an alkali metal silicateThe solution made within the limits of the above so formula should be aclear liquid of approximately to 32 Baum. One part by volume of thissolution is then mixed with from 5 to 60 parts of common moidi sanddepending upon the use for whi the product is being made.

I have discovered further that certain qualities of the cores madeaccording to the above prescribed practice may be greatly improved byslight variations in the proportions of the materials set forth above,and bythe addition thereto of a bitumen preferably emulsified such, for

example, as an emulsion of fit.

I have also vered that the use of a bituminous, emulsion such as anemulsion of asphalt in combination with the above solution in making asand core has several advantages. It makes a core that will break upreadily after it has been used. This is an important feature of themanufacture of cores, because where cores are made sufiiciently durableto withstand the en'ect of molten metal being poured against them. theyareinsomecasessohardthatitisdiflicultto remove the core from the castingafter the castinghascooled. Easyremovalofthecoreisparin cases where thecore forms smallorirregularesinthecastingsuch. for example, as the waterjacket or block in the cylinder head of an internal combustion engine.Inmakingsuchacastingwithcoresmadeinaccordance with the presentinvention, the cores have not only stood up \mder pouring in a mannerwhich compares favorably with the finest cores made by other methods,but after cooling of the casting, a slight jar is suflicient to socompletely break up the core that it may be poured from the casting in afinely divided granular condition.

A further advantage of cores made accordin to the present invention isthat they may be dried or cured very quickly without harmful results.For example, cores havinga wall thickness of approximately two inchesmay be completely cured by an exposure to a temperature of about 500 F.for a period of fifteen minutes or less. The presence of the bitmninousemulsion in the core also effects a uniformity in the curing process inthat a core made in this manner is found to dry with a uniform hardnessthroughout, whereas the same core with the emulsionomittedhasatendencyto dryorcureharderin some parts than in others, andusually harder in the lower regions of the core, which is probably dueto the fact that the bindin materials used with the sand have a tendencyto drain to-. ward or collect at the bottom of the core before 5 it iscompletely cured. The asphalt also produces the very desirable result ofpreventing adherence of the core to the box or form in which it ismolded so that the production of a perfectcoreismademoreeasybytheeliminationofw 1750 c. 0. dry nd 125 c. c. of aso u on of approximately: 2 gallons water l-lO ounces aluminum sulphate1-10 ounces alkali fluosilicate. and 1-10 gallons of an alkali metalsilicate 40 c. c. of an asphalt emulsion 65 c. c. of water In mixing,the emulsion is preferably first added to the solution and thoroughlystirred and then the water is added, the stirring being continued 10 toinsure thorough mixing and distribution of the emulsion and thesolution. The resulting liquid is added to the sand in a manner toimpart an even distribution of moisture and uniform molding qualities tothe sand. Where the sand :5 to be used is not perfectly dry, the waterin the mixture may be reduced slightly to obtain the same ultimateresult.

I have referred to sand as one ingredient of my core. and it should beunderstood that the '0 term "sand as used herein in the appended claimsis any type of molded sand or other granular material capable of beingused in this mannet.

The invention as described above pertains to molded cores of all typesused in foundry practice and similar practices.

Having thus described my invention, what I claim and desire to secure byLetters Patent isl. A molded product comprising sand and a binder of analkali metal silicate, an alkali metal nuosillcate, aluminum sulphate,and a bitumi- 5 nous emulsion.

2. A molded product comprising a mixture or sand, a binder whichconsists principally of about 2 gallons of water l-lO ounces of aluminumsulphate m 1-10 ounces of an alkali metal fluosilicate l-10 gallons ofan alkali metal silicate and a bituminous emulsion.

8. A molded product comprising a mixture of 1s sand, a binder whichconsists principally of about 2 gallons of water 1-10 ounces of aluminumsulphate 1-10 ounces of sodium fluosilicate 140 gallons of sodiumsilicate and a bituminousemulsion.

4. A molded product comprising sand, a liquid binder and an asphaltemulsion, said liquid binder comprising an aqueous solution obtained byvan-Ilium. unezisqxam in: it slqmr;

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